/*
 * Copyright 2012-2021 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot;

import org.springframework.context.ApplicationContext;

/**
 * 用于添加或移除 JVM 关闭时应执行代码的接口。关闭处理器类似于 JVM 的
 * {@link Runtime#addShutdownHook(Thread) shutdown hooks}，但它们是顺序执行的，
 * 而非并发执行。
 * <p>
 * 关闭处理器保证只在已注册的 {@link ApplicationContext} 实例关闭且不再活跃后被调用。
 *
 * @author Phillip Webb
 * @author Andy Wilkinson
 * @since 2.5.1
 * @see SpringApplication#getShutdownHandlers()
 * @see SpringApplication#setRegisterShutdownHook(boolean)
 */
public interface SpringApplicationShutdownHandlers {

	/**
	 * 添加一个将在 JVM 退出时运行的操作。
	 * @param action 要添加的操作
	 */
	void add(Runnable action);

	/**
	 * 移除之前添加的操作，使其在 JVM 退出时不再执行。
	 * @param action 要移除的操作
	 */
	void remove(Runnable action);

}
